From a25054e4fcfdb40fb11ee7ddcddbb24ec3ebe80b Mon Sep 17 00:00:00 2001 From: Thadeu Lima de Souza Cascardo Date: Tue, 9 Aug 2022 14:05:18 -0300 Subject: [PATCH] net_sched: cls_route: remove from list when handle is 0 commit 164cb04497f2eecc2e9b4a1f65377968d4be7388 upstream. When a route filter is replaced and the old filter has a 0 handle, the old one won't be removed from the hashtable, while it will still be freed. The test was there since before commit 56e0e5d62434 ("net: sched: RCU cls_route"), when a new filter was not allocated when there was an old one. The old filter was reused and the reinserting would only be necessary if an old filter was replaced. That was still wrong for the same case where the old handle was 0. Remove the old filter from the list independently from its handle value. This fixes CVE-2022-2588, also reported as ZDI-CAN-17440. Reported-by: Zhenpeng Lin Signed-off-by: Thadeu Lima de Souza Cascardo Reviewed-by: Kamal Mostafa Cc: Acked-by: Jamal Hadi Salim Link: https://lore.kernel.org/r/20220809170518.164662-1-cascardo@canonical.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/sched/cls_route.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c index a35ab8c27866e..3f935cbbaff66 100644 --- a/net/sched/cls_route.c +++ b/net/sched/cls_route.c @@ -526,7 +526,7 @@ static int route4_change(struct net *net, struct sk_buff *in_skb, rcu_assign_pointer(f->next, f1); rcu_assign_pointer(*fp, f); - if (fold && fold->handle && f->handle != fold->handle) { + if (fold) { th = to_hash(fold->handle); h = from_hash(fold->handle >> 16); b = rtnl_dereference(head->table[th]); -- 2.39.5